would those burning questions about america's involvement in libya, president obama just laid out his plans to the nation. phil matier listened in on his address. phil. >> reporter: this was president obama's most detailed speech on what the united states hopes to accomplish with the new military mission in libya and the president forcefully said that libyan leader moammar qaddafi left him little choice but to act. he said the u.s. acted to prevent a massacre. >> 10 days ago, having tried to end the violence without using force, the international community offered qaddafi a final chance to stop his campaign of killing or face the consequences. rather than stand down, his forces continued their advance bearing down on the city of benghazi home to nearly 700,000 men, women and children who sought their freedom from fear. >> reporter: the president went to great lengths to me assure the nation that the u.s. is not interested in regime change. that would take years he said and millions if not trillions of dollars. the burden of actions should not be america's alone, he said. >> the transi